This invention generally relates to guiding members for vascular catheters useful in such procedures as angiography, angioplasty, valvuloplasty and the like.
In typical percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced therein until the distal tip thereof is in the ostium of the desired coronary artery. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced into the patient's coronary vasculature until the distal end thereof crosses the lesion to be dilated and then the dilatation catheter is advanced over the previously introduced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, relatively inelastic balloon is inflated to radially compress atherosclerotic plaque against the inside of the artery wall to thereby dilate the lumen of the artery. The balloon is then deflated so that the dilatation catheter and the guidewire can be removed and blood flow resumed through the dilated artery.
Guidewires for vascular use usually comprise an elongated core member which is tapered toward the distal end, a helical coil disposed about and secured to the tapered distal end of the core member and a rounded plug provided on the distal tip of the coil. Preferably, the plug and at least part of the coil are formed of highly radiopaque materials to facilitate fluoroscopic observation thereof. There are two general types of guidewire constructions. In the first type, the core member extends through the coil to the plug in the distal tip thereof. In the second type, the core member extends into the interior of the helical coil, but terminates short of the plug in the distal tip. A shaping ribbon is secured directly or indirectly to the core member and the ribbon is secured to the radiopaque plug as shown.
Steerable dilatation catheters with built-in or fixed guidewires or guiding elements are used with greater frequency because the deflated profile of such catheters is generally smaller than conventional dilatation catheters with movable guidewires or elements having the same inflated balloon size.
Further details of angioplasty procedures and the devices used in such procedures can be found in U.S. Pat. No. 4,332,254 (Lundquist); U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.) U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); and U.S. Pat. No. 4,616,652 (Simpson). Each of the above references is incorporated herein in their entirety.
Further details about guidewires can be found in U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.) U.S. Pat. No. 4,619,274 (Morrison); and U.S. Pat. No. 4,721,117 (Mar et al.).
Further details of low-profile steerable dilatation catheters may be found in U.S. Pat. No. 4,582,181 (Samson); U.S. Pat. No. 4,619,263 (Frisbie et al.); U.S. Pat. No. 4,641,654 (Samson et al.); and U.S. Pat. No. 4,664,113 (Frisbie et al.).
While the prior guidewires and guide members have for the most part performed well, there was always a need for increased flexibility and the increased torquability and pushability of the distal tip of the guidewire. With the prior devices, improvements in flexibility usually involved some loss of torquability and improvements in torquability usually involved some loss in flexibility. What has been needed and heretofore unavailable is some means to improve both the flexibility and torquability of the distal tip of the guidewire. The present invention satisfies that need.